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Rhodobacterales use a unique L‐threonine kinase for the assembly of the nucleotide loop of coenzyme B 12
Author(s) -
Tavares Norbert K.,
VanDrisse Chelsey M.,
EscalanteSemerena Jorge C.
Publication year - 2018
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.14100
Subject(s) - rhodobacter sphaeroides , biology , corrin , rhodobacter , adenosylcobalamin , complementation , biochemistry , threonine , mutant , nucleotide , cofactor , enzyme , microbiology and biotechnology , gene , photosynthesis , serine , vitamin b12
Summary Several of the enzymes involved in the conversion of adenosylcobyric acid (AdoCby) to adenosylcobamide (AdoCba) are yet to be identified and characterized in some cobamide (Cba)‐producing prokaryotes. Using a bioinformatics approach, we identified the bluE gene (locus tag RSP_0788) of Rhodobacter sphaeroides 2.4.1 as a putative functional homolog of the L‐threonine kinase enzyme (PduX, EC 2.7.1.177) of S. enterica . In AdoCba, ( R )‐1‐aminopropan‐2‐ol O ‐phosphate (AP‐P) links the nucleotide loop to the corrin ring; most known AdoCba producers derive AP‐P from L‐Thr‐ O ‐3‐phosphate (L‐Thr‐P). Here, we show that Rs BluE has L‐Thr‐independent ATPase activity in vivo and in vitro . We used 31 P‐NMR spectroscopy to show that Rs BluE generates L‐Thr‐P at the expense of ATP and is unable to use L‐Ser as a substrate. BluE from R. sphaeroides or Rhodobacter capsulatus restored AdoCba biosynthesis in S. enterica Ε pduX and R. sphaeroides Ε bluE mutant strains. R. sphaeroides Ε bluE strains exhibited a decreased pigment phenotype that was restored by complementation with BluE. Finally, phylogenetic analyses revealed that bluE was restricted to the genomes of a few Rhodobacterales that appear to have a preference for a specific form of Cba, namely Coᴽ ‐( ᴽ ‐5,6‐dimethylbenzimidazolyl‐ Coᵦ ‐adenosylcobamide (a.k.a. adenosylcobalamin, AdoCbl; coenzyme B 12 , CoB 12 ).